Voting Button Tracking Tab, tracking wrong person (Outlook 2003)

Here is my problem. I sent out a message with a voting button Yes/No to a group of managers. Some of the assistants' have access to their managers' mailbox. These assistants replied 'On Behalf Of' their manager. When I look in my tracking tab, the managers have no response and then the assistant's name is added. I realize that it is the assistant who is sending the message, but since it's coming on behalf of the manager, shouldn't it be from the manager in my tracking tab. Is there a way to fix this. It makes it difficult as I have to go through my list and match assistants to managers. I've already called a few managers and asked them to respond, only to later find out that their assistant's already had.